The present invention relates to a technical art for suppressing and reducing sound that is generated by a fuel supply system of a V-type engine.
In the fuel supply system of a V-type engine, fuel under pressure supplied by a fuel pump is subjected to a controlling in pressure by a pressure regulating valve, and is supplied to a fuel supply conduit having a portion thereof arranged to straddle between the cylinder heads disposed in the two V-like banks of the V-type engine. The fuel is further distributed from the fuel supply conduit to fuel-injection valves provided for the respective cylinders of the V-type engine, via respective fuel distribution conduits provided for the cylinders in the two banks; of the V-type engine. The above-described arrangement of the fuel supply system of the V-type engine is disclosed in the Laid-open Japanese Patent Publication No. 8-334032.
In the disclosed prior art fuel supply system of the V-type engine, the portion of the fuel supply conduit that is arranged to straddle between the cylinder heads of the two banks is supported at its opposite ends only, and accordingly the mechanical rigidity in supporting that portion of the fuel supply conduit is small. Thus, while the fuel injection valves are operating, the less rigid fuel supply conduit portion often becomes a sound source generating a large working sound of the fuel injection valves, which includes a sound component due to the driving of the fuel injection valves and a vibratory sound component due to a change in the pressure of the fuel that occurs during the injection of the fuel toward the respective cylinders of the V-type engine. In particular, in the direct-injection type engine, which has recently become the majority in the V-type engines, the fuel injection must be done under a high pressure, and accordingly the fuel is pressurized to have a rather high pressure by a high-pressure type fuel pump before it is supplied to the respective fuel injection valves. Consequently, the working sound that is generated by the fuel injection valves in operation has become an unignorable problem requested to solve.
Therefore, an object of the present invention is to solve the problem encountered by the fuel supply system of the V-type engine according to the prior art.
Another object of the present invention is to provide a high rigidity support structure for a fuel supply conduit of a fuel supply system, specifically a fuel supply conduit portion of the fuel supply conduit, which is arranged to straddle between the cylinder heads of both banks of a V-type engine, so that the working sound of the fuel injection valves generated by and transmitted from the fuel supply conduit portion may be satisfactorily suppressed and reduced.
Taking into account the above objects, according to the present invention, there is provided a support structure for a fuel supply conduit portion of a fuel supply conduit that is arranged to straddle between the cylinder heads of both banks of the V-type engine, the support structure being constituted by a mechanical connection that connects a generally intermediate portion of the fuel supply conduit portion to a water jacket member extending to bridge between the cylinder heads of both banks of the V-type engine and rigidly fixed at its opposite ends to the cylinder heads. Thus, the support structure for the fuel supply conduit portion straddling between the cylinder heads of both banks of the V-type engine can provide the same bridge-conduit portion with a highly rigid support due to the mechanical connection provided between the fuel supply conduit portion and the water jacket member, so that any vibratory motion which might occur in the fuel supply conduit portion straddling between the cylinder heads of both banks of the V-type engine can be prevented. As a result, the working sound of the fuel injection valves that is generated by the fuel supply conduit portion can be suppressed and reduced. Particularly, since the fuel supply conduit portion of the fuel supply system is eventually connected to the engine body at a position adjacent to the center of vibration of the engine, the fuel supply conduit portion of the fuel supply system supported by the support structure is not permitted to cause any resonant vibration with the engine vibration. Therefore, the generation of the working sound of the fuel injection valves by the fuel supply conduit portion of the fuel supply system of the V-type engine can be effectively suppressed and reduced.
The above and other objects, features and advantages of the present invention will be made more apparent from the ensuing description of the following description of a preferred embodiment thereof with reference to the accompanying drawings.